1. Field of the Invention
The present invention relates to a fuel control system for supercharged, fuel injected internal combustion engines, in particular diesel engines employing exaust gas turbo-chargers. The individual control units of the control system each comprise a movable partition which is displaceable against the force of at least one return spring in dependence on the intake air pressure of the engine. The movable partitions are connected to a setting member by means of which the operating region of a supply quantity adjustment member of the engine injection system is changeable in the direction of increasing supply quantity during a period of increasing intake manifold air pressure.
2. Description of the Prior Art
Known control systems of the above-mentioned construction which are also designated as manifold pressure dependent full load stops or smoke limiters, are installed either at the injection pump or at the corresponding regulator of the engine, and their setting member influences either the position of a full load stop for the limitation of the control rod path or it limits the maximum excursion of the adjustment lever of the regulator attached to the injection pump, or again, it interacts with the control linkage in such a way as to change the position of the control rod of the injection pump from that which may have been set by the regulator to a new position lying further in the direction of increasing supply quantity, the magnitude of the change depending on the magnitude of the intake manifold air pressure. These known control systems have the disadvantage that the controlled increase of the fuel quantity during acceleration of the engine occurs with a time delay, because the manifold air pressure is used to measure the fuel increase and, in engines employing exhaust gas turbo-chargers, the manifold air pressure increases only after an increase of the exhaust gas pressure and of the exhaust gas temperature. This mutual dependence of fuel quantity, intake manifold pressure and exhaust gas pressure determines the acceleration characteristics of an engine equipped with an exhaust gas turbo-charger and employing the known control system. These acceleration characteristics are often incapable of meeting the demands made especially on modern vehicular diesel engines.
In order to achieve a more rapid acceleration of the engine, it would be possible, in principle, to increase the fuel quantity metered by the control system so that the desired acceleration of the engine would be achieved. This method has the considerable disadvantage, however, that during full load operation and during constant speed operation, the engine then develops inadmissible amounts of smoke.